ISO 8781-1:1990 PDF

Pigments and extenders — Methods of assessment of dispersion characteristics — Part 1: Assessment from the change in tinting strength of coloured pigments

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Title (English):

ISO 8781-1:1990

Pigments and extenders — Methods of assessment of dispersion characteristics — Part 1: Assessment from the change in tinting strength of coloured pigments

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 5
Publication date:: November 15, 1990
Edition:: ISO IS 8781 edition 1 version 1
ICS:: 87.060.10

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Description (English):

Relates to coloured pigments which have been dispersed by one of the methods described in ISO 8780. The method is of general use for comparing similar pigments, for example a test pigment against an agreed reference pigment. The principle consists in dispersing the pigment in stages under specified conditions in an agreed binder system. After each dispersion stage, a portion of the mill base is taken and mixed separately with a white pigment to form a reduced paste. The tinting strength of each reduced paste is determined as described in ISO 787-24. The percentage increase in tinting strength between two dispersion stages is calculated in order to assess the ease of dispersibility of the pigment.

Technical details

Technical committee: ISO/TC 256 - Pigments, dyestuffs and extenders
SKU: ISO 8781-1:1990

Abstract

Overview

ISO 8781-1:1990 defines a standardized laboratory method for assessing the dispersion characteristics of coloured pigments by measuring changes in tinting strength during staged dispersion. The method applies to pigments dispersed according to one of the procedures in ISO 8780 and is intended mainly for comparative tests (for example, a test pigment versus an agreed reference pigment). Tinting strength is quantified as a K/S value (per ISO 787-24) of reduced pastes made by mixing incremental mill-base samples with a white pigment paste.

Key Topics and Requirements

Scope: Coloured pigments dispersed in an agreed binder system using ISO 8780 dispersion methods.
Core principle: Prepare pigment dispersions in stages, take samples after each stage, mix each sample with a white pigment paste to form a reduced paste, and measure tinting strength (K/S).
Measurement: Photometric or spectrometric measurement of reflectance (400–700 nm) and calculation of K/S values following ISO 787-24.
Result expression: Calculate percentage increase in tinting strength (IS) between two agreed dispersion stages using IS = ((K/S)2 – (K/S)1) / (K/S)1 × 100. Optionally plot K/S vs. work input (or reciprocals) to determine development curves and ultimate tinting strength.
Apparatus & materials: Balance, film applicator, automatic muller (for high-viscosity binders), spectrometer or photometer, agreed white pigment (typically TiO2 grade R2 per ISO 591 unless otherwise agreed).
Supplementary information (Annex A): Must specify dispersion method (ISO 8780 part), white pigment type, reduction ratio, film application method, data presentation and any reference pigment.
Interpretation: Guidance on significance - e.g., IS between 0–20 is not significant unless >7; in ranges 50–100 a difference >12 is considered significant. Graphical anomalies (peaks or troughs) may indicate overgrinding, flocculation or recrystallization.

Applications and Users

Quality control laboratories comparing batch dispersibility of pigments.
Pigment and paint manufacturers for product development and supplier qualification.
Coatings, inks and plastics formulators selecting pigments for ease of milling and color development.
R&D teams troubleshooting dispersion issues (e.g., overgrinding or flocculation) and optimizing milling parameters.

Related Standards

ISO 8780 (Parts 1–6): methods of dispersion (oscillatory shaking, high-speed impeller, bead mill, automatic muller, triple-roll mill, etc.)
ISO 787-24: determination of relative tinting strength (photometric methods)
ISO 591: titanium dioxide pigments - specifications
ISO 105-A01: general principles of colour fastness testing

Keywords: ISO 8781-1, tinting strength, dispersion characteristics, coloured pigments, K/S value, reduced paste, pigment dispersibility, ISO 8780, ISO 787-24, titanium dioxide.

Related standards

Other ISO standards

Abstract

Overview

Key Topics and Requirements

Scope: Coloured pigments dispersed in an agreed binder system using ISO 8780 dispersion methods.
Core principle: Prepare pigment dispersions in stages, take samples after each stage, mix each sample with a white pigment paste to form a reduced paste, and measure tinting strength (K/S).
Measurement: Photometric or spectrometric measurement of reflectance (400–700 nm) and calculation of K/S values following ISO 787-24.
Result expression: Calculate percentage increase in tinting strength (IS) between two agreed dispersion stages using IS = ((K/S)2 – (K/S)1) / (K/S)1 × 100. Optionally plot K/S vs. work input (or reciprocals) to determine development curves and ultimate tinting strength.
Apparatus & materials: Balance, film applicator, automatic muller (for high-viscosity binders), spectrometer or photometer, agreed white pigment (typically TiO2 grade R2 per ISO 591 unless otherwise agreed).
Supplementary information (Annex A): Must specify dispersion method (ISO 8780 part), white pigment type, reduction ratio, film application method, data presentation and any reference pigment.
Interpretation: Guidance on significance - e.g., IS between 0–20 is not significant unless >7; in ranges 50–100 a difference >12 is considered significant. Graphical anomalies (peaks or troughs) may indicate overgrinding, flocculation or recrystallization.

Applications and Users

Quality control laboratories comparing batch dispersibility of pigments.
Pigment and paint manufacturers for product development and supplier qualification.
Coatings, inks and plastics formulators selecting pigments for ease of milling and color development.
R&D teams troubleshooting dispersion issues (e.g., overgrinding or flocculation) and optimizing milling parameters.

Related Standards

ISO 8780 (Parts 1–6): methods of dispersion (oscillatory shaking, high-speed impeller, bead mill, automatic muller, triple-roll mill, etc.)
ISO 787-24: determination of relative tinting strength (photometric methods)
ISO 591: titanium dioxide pigments - specifications
ISO 105-A01: general principles of colour fastness testing

Keywords: ISO 8781-1, tinting strength, dispersion characteristics, coloured pigments, K/S value, reduced paste, pigment dispersibility, ISO 8780, ISO 787-24, titanium dioxide.

ISO 8781-1:1990 PDF

Technical details

Abstract

Overview

Key Topics and Requirements

Applications and Users

Related Standards

Related standards

Abstract

Overview

Key Topics and Requirements

Applications and Users

Related Standards

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